This invention relates to roof support systems and, more particularly, to a roof support apparatus for a mine.
Roof trusses or roof support systems for mines, although a fairly recent innovation, are now commonly used in, for example, coal mines to provide support to the immediate roof strata. A typical roof truss system utilizes a tie rod or truss member placed parallel to the roof of the mine, and a roof bolt angled into the mine roof at each end of the member. The truss member is placed in tension to create stresses in the immediate roof area; these stresses being compressive stresses exerted in both the vertical and horizontal directions. One such system is described in U.S. Pat. No. 4,601,616 (Barisha et al) which discloses the use of single connector plates between the inclined anchor rods and a compound tie rod which utilizes turnbuckle-like coupling sleeves.
While the roof truss support systems are generally useful, present systems do have some shortcomings. Among these are a failure to physically apply upward thrust to the immediate roof strata away from the angle bolts; truss systems must be installed outside of normal production cycle because of long installation time required; the truss systems are not capable of controlled yielding as ground movements occur; and, there is no load measuring device for reading the load acting on the system at any one time.
The present apparatus solves these and other problems in a manner not disclosed in the known prior art.